Amiga and Others  
                            ~~~~~~~~~~~~~~~~
                          Part I: The Hardware

                             by Andrew Wong



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Contents
0. Introduction
1. The CPU and Memory
2. Expandability
3. Expansion Standards
4. Disk Drives
5. Video
6. Audio
7. Keyboard and Mouse
8. Operating Systems' Hardware Requirements
9. In the Next Part


0. Introduction
  In a letter published in MD33 Chris Searle expressed interest in a `honest
  no-holds-barred comparison of the Amiga Workbench Version 2xx and Windows
  3.1 on MSDos machines'.  This series of articles attempts such a task.  In
  it I compare from the user's point-of-view:

    ˇ Amiga computers running AmigaDOS 2.0 or greater;
    ˇ IBM PC-compatible computers (hereafter referred to as PCs) running
      MS-DOS 5.0 or 6.0, Microsoft Windows 3.1, and IBM OS/2 2.0 or 2.1;
      and
    ˇ Macintosh computers running System 7.0 or 7.1.

   The emphasis is on the first two listed.  I have had little experience
  with the Atari ST and have therefore not included it in this series of
  articles.  As the ST and Amiga are similar in many respects I hope someone
  else will take this up.

   In accordance with Chris's suggestion the comparison will primarily be of
  the operating systems and user interfaces, but we will begin the series
  with a brief overview of the hardware involved.


1. The CPU and Memory
  There is not much to be said about the CPU in each system except that the
  Amiga and Macintosh use Motorola processors - 68000, 68010, 68020, 68030,
  and 68040 - and PCs conventionally use Intel processors.  The main CPUs in
  the Intel family are the 8086, 80286, 80386, and i486, but Intel, for
  commercial reasons, has also released the 386SX and 486SX chips -
  downgraded versions of the 80386 and i486 respectively - causing the
  corresponding full-specification CPUs to be referred to as the 386DX and
  486DX.  True to the spirit of cloning that characterises the entire PC
  market several other manufacturers such as Cyrix have introduced clones of
  the Intel chips, with names like 486SLC, at much lower prices.

   Memory, on the other hand, is a big problem for some computers.  The
  Macintosh has only one type of memory and as such is one of the simplest
  machines in this regard.  The Amiga has two types of memory - Chip RAM and
  Fast RAM, the former being the only type accessible to the custom chips -
  and overcoming the division between the two types has not been easy; the
  maximum amount of Chip RAM differs with each Amiga model, and Chip RAM is
  much slower than Fast RAM; the result is that users who work with sound and
  graphics want more Chip RAM and other users want more Fast RAM.

   None of the Amiga's problems, however, compare to those of the PC.  The
  problems originate from the IBM PC's 8088 CPU, which had a 1MB address
  space.  The IBM engineers assigned 640KB of that 1MB as the computer's RAM
  and the other 384KB were to be reserved for the ROM.  As the PC became
  popular and more memory was needed Lotus, Intel, and Microsoft devised a
  way more memory could be added while still working with the CPU's limited
  address space; this was called expanded memory.  When the 80286 CPU, which
  had a 16MB address space, was introduced a new, simpler model for adding
  memory was created called extended memory.  When the 80386 CPU was
  introduced its memory management capabilities allowed it to use extended
  memory to simulate expanded memory and to allocate unused regions in the
  384KB reserved area as RAM.

   None of all this solved the problem that MS-DOS could in general use only
  640KB of RAM in which to run programs.  This was one of the reasons behind
  Windows.  Windows applications are not restricted to 640KB of RAM and can
  access extended memory freely.  OS/2 was created to replace MS-DOS and
  Windows entirely; it too has a flat memory model, and OS/2 applications
  have only one type of memory to access.

   Notwithstanding, memory in the PC, especially for MS-DOS users, is a mass
  of jargon and acronyms.  The first 640KB of RAM is called conventional or
  low memory; the next 384KB is called reserved or high or upper memory; the
  first 64KB of extended memory is called the High Memory Area (HMA).  The
  standard for adding extended memory to the system is called the
  Lotus-Intel-Microsoft (LIM) Expanded Memory Specification (EMS); the device
  driver that manages its operation is called an expanded memory manager
  (EMM).  The standard for adding extended memory is the Extended Memory
  Specification (XMS).  Portions of upper memory used as RAM on a 386-based
  system are called Upper Memory Blocks (UMBs).  Then there are the DOS
  drivers: the XMS driver, also responsible for the HMA, is called HIMEM.SYS;
  the EMS emulator and UMB manager is called EMM386.EXE.


2. Expandability
  The expandability of the Amiga and Macintosh depend on the model, but most
  PCs these days have an ample number of expansion slots available.  PCs are
  often criticised for having very few facilities on the system board; but
  that is a part of the open architecture principle.  Most PCs have only the
  CPU, ROM, and memory, on the system board and require additional cards for
  the video display, any sound capabilities beyond that of the PC speaker,
  serial and parallel and joystick ports, and hard disk drive and floppy disk
  drive interfaces.  Of the 7 or 8 slots usually provided about 4 are used
  for these, leaving 3 or 4 free slots.  This compares fairly well with the
  number of slots available on other computers.

   Hardware compatibility can be a problem on the PC, particularly if non-
  standard cards such as an unusual display card, scanner card, or network
  card are installed.  These will often result in a conflict of interrupt
  request lines (IRQs) and memory addresses between different cards.  In some
  cases one can even run out of these resources, such as on an XT-class
  computer, which has only eight IRQs available, most of which are already
  used by either the system or other devices such as the serial port or hard
  drive.

   The Amiga has an advantage in this respect because its expansion slots are
  governed by a system called Autoconfig, which allows the system to
  automatically recognise and configure an expansion card.


3. Expansion Standards
  The Amiga and Macintosh are strictly proprietory systems and both have
  well-defined standards for adding expansion cards, video cards, disk
  drives, and so on.  PCs are different in that they have an open market:
  manufacture of the hardware is not restricted to one company.  It is this,
  together with the PCs age, its popularity - leading to the huge numbers of
  manufacturers that now exist - and its completely open architecture -
  creating markets for just about everything that constitutes a complete PC -
  that has lead to a jumble of hardware standards as complicated as anything
  else on the PC.

   In some cases, established standards do exist, but there are several of
  them to choose from.  For instance, the standard for expansion cards
  depends on the type of system board: PC-XT-class machines have an 8-bit
  expansion bus, AT-class machines have a 16-bit bus commonly called Industry
  Standard Architecture (ISA), IBM created a 32-bit bus called Micro Channel
  Architecture (MCA), other manufacturers rebelled and created the Extended
  ISA bus (EISA), and a recent development is the local bus for which no
  `official' standard exists but the VESA VL-Bus is the most common.

   Some PC standards are not established by a particular organisation, but
  exist as de facto standards.  For example, video standards were mostly
  defined by IBM - CGA, EGA, VGA, XGA, and so on; above VGA the de facto
  standard is SVGA or Super VGA, meaning 800x600 resolution with 16 colours,
  but above SVGA there are no standards.  Other standards are based on
  products and manufacturers that are popular and have therefore had
  influence in the marketplace: the standard mouse is Microsoft's; the
  standard sound card is the SoundBlaster or AdLib.

   The Small Computer Systems Interface (SCSI) standard was created to
  provide a common standard for peripherals between all systems.  In this
  way, SCSI hard drives, backup tape drives, scanners, and so on can be
  connected to, say, an Amiga or a Macintosh without modification.
  Unfortunately, something has gone astray with this principle on PCs and a
  SCSI CD-ROM drive, for example, will not necessarily work with any given
  SCSI controller card.


4. Disk Drives
  The Amiga's floppy drive seems to have improved recently, but for many
  years it has been an embarrasment; while other computers had quiet and
  efficient floppy drives the Amiga's drive was incomprehensibly slow and
  noisy.  Being a multitasking computer, the Amiga was also prone to disk
  thrashing - a condition in which the floppy drive made a great deal of
  grinding noises while getting very little accomplished.

   The PC has the problem of having at least four commonly-used floppy disk
  formats: 3.5-inch and 5.25-inch disks, both available in double-density and
  high-density.  It is a problem that stems from the PC's age and makes
  working with floppy disks very frustrating.


5. Video
  This topic will be covered in the next part of this series in order to be
  integrated with a discussion on how the operating system utilises graphics
  and what graphics modes it supports.


6. Audio
  The Amiga's sound quality has for some time been amongst the best available
  and still compares well to that of other machines.  Unfortunately, the
  Amiga sound chip has not kept ahead of the competition and, while other
  machines have improved in this regard, the Amiga has stood still; as far as
  concerns sound quality today's Amiga is all but identical to the original
  A1000.

   The sound in a PC is normally generated through a built-in speaker, and
  the quality is abysmal.  It was years after the PC's release before a sound
  card was developed, which enabled games and other software to make pleasant
  sounds, but, until recently, sound cards for some reason still did not
  sound as good as an Amiga, despite their ostensibly higher specifications.
  However, 16-bit sound cards were introduced on the PC last year, which were
  much more impressive than the older cards; and sound cards, particularly
  the 8-bit type, are now so inexpensive that all PC users should be able to
  afford one.


7. Keyboard and Mouse
  One would think that the keyboard and mouse are hardly worth mentioning,
  but they are the main input devices and as such can reflect something about
  a computer's design.  The Macintosh has a one-button mouse, which fits it
  well with many people's impression of the Macintosh as a computer that is
  easy to use and well-suited to novices, but limited in flexibility for more
  advanced users.  Having one button makes it impossible to select the wrong
  one, but Amiga and Windows users will know that a second button can be very
  useful in some applications; the Amiga Workbench and OS/2 also use the
  second button to select menus.  That the Mac mouse is of high quality while
  the Amiga mouse is, well, crap may even say something about the companies
  that manufactured them.

   Although Apple strenuously asserts that consistency is one of the
  Macintosh's best qualities the Mac keyboard is oddly out of line with this
  principle: the Mac has had at least four different keyboards and on each
  one the cursor keys, Control key, Option key, backtick and backslash keys,
  Escape key, and Enter key have been moved all around, and the Delete key
  has had two different names.


8. Operating Systems' Hardware Requirements
  The hardware requirements of an operating system can give some indication
  of its complexity and sophistication.  It can also reflect its intended
  market: the Amiga's scant requirements, for example, make it suitable for
  small systems; by contrast, Microsoft's latest operating system, Windows
  NT, will need some 16MB of RAM to run efficiently.

   The Amiga's requirements are astonishingly small: 256KB of RAM and a
  floppy disk drive, although for efficiency 1MB of RAM and either two floppy
  drives or a hard drive are needed.

   The Macintosh requires a minimum of 2MB and `a hard drive' for System 7,
  though 4MB is better.

   MS-DOS requires 512KB of RAM and one floppy drive, but a workable
  environment would include at least 1MB RAM and a hard drive.  The Amiga is
  much more capable in its minimum configuration than MS-DOS is, but MS-DOS
  is considerably leaner than Windows, which is why some PC users prefer to
  stick with DOS.

   Windows requires a 286 processor, 1MB RAM, and 6.5MB of hard disk space,
  but a 386SX processor, 4MB RAM, and 10.5MB of hard disk are highly
  recommended.  Multitasking programs in Windows (which is treated more
  thoroughly in the next part of this series) requires more memory to be
  effective; I noticed a significant improvement in speed when I upgraded my
  PC from 4 to 8MB of RAM.

   Supposedly, OS/2 needs a minimum of a 386SX processor, 4MB RAM, and 15MB
  of hard disk space, but it is unusably slow in this configuration, and due
  to bugs in the version 2.0 installation software it might not install at
  all.  The recommended minimum is a 386DX processor, 8MB RAM, and 50MB of
  hard disk space.  With OS/2 more is better.


9. In the Next Part
  In Part II of this series we shall examine the operating systems in detail,
  including video modes, command-line environments, graphical user
  interfaces, file systems, multitasking, and more.  A future article will
  examine the philosophy and principles of the operating systems and evaluate
  each computer's position and future in the marketplace.



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